/Engine/Source/Runtime/Engine/Classes/AI/Navigation/NavigationTypes.h
There should be one of these Ids generated and stored per Actor or Component that inherits fromINavLinkCustomInterface. Primarily its a way of differentiating between Components that inherit fromINavLinkCustomInterfaceas the ActorInstanceGuid alone can not do this.SeeUNavLinkCustomComponentas an example. For Level Instances these will be different for each component in an actor but repeated in repeated Level Instances.FNavLinkId::GenerateUniqueId() uses this to make the UniqueId
struct FNavLinkAuxiliaryId